Mt. CB adopts Exterior Energy Offset Program

Mitigating energy usage for new and renovated outdoor systems

By Kendra Walker

Over the past year the town of Mt. Crested Butte has been working on initiatives toward additional sustainability and climate action planning, and after a series of work sessions and council meetings throughout the year, the town council recently approved its latest program to address energy use from exterior energy systems such as heated driveways.

At the beginning of this year, the council’s adoption of the 2021 Building Codes and the Colorado Model Energy Codes went into effect to improve energy efficiency compared to the 2015 codes. The town has also been collaborating with local engineering firm, Resource Engineering Group (REG), to develop options for both interior and exterior energy mitigation for new construction and large renovations.

To address energy use from exterior energy systems, such as snowmelt, outdoor gas fireplaces, large hot tubs and pools, town staff has worked with the council to develop an Exterior Energy Offset Program (EEOP). The goal of an Exterior Energy Offset Program is to educate homeowners on the excessive energy used by these outdoor energy systems and to mitigate the energy they use.

According to town planner Shannon Hessler, snowmelt systems use twice as much energy per square foot as indoor heating systems.

A REG study done in Crested Butte found that using snow removal equipment like snowblowers or plows is 100 times less carbon-intensive than snowmelt systems.

“Installing multiple exterior energy systems –– like a combination of the following: more than one hot tub, outdoor fireplaces, outdoor plumbed kitchen appliances, large heated driveways, etc. –– will require the homeowner to reconsider the design of their project,” explained Hessler of the EEOP. “Ideally, we’d like them to not install the exterior energy system that heats the outdoors! But if they still want those systems, they have the option to mitigate their energy use on-site, using a renewable energy source like rooftop solar, or pay a fee in lieu, which is the equivalent of the cost to build that solar system.”

The EEOP requires new construction and major renovations of existing exterior energy systems to offset the energy use through on-site renewable energy or by paying a fee in lieu. “The fee will be paid into a sustainability fund which will fund projects that directly produce renewable energy in Mt. CB or increase energy efficiency in Mt. CB,” said Hessler.

With input from the town council, REG created an EEOP Calculator Tool to calculate the solar mitigation/fee in lieu amounts. The town also received feedback from local contractors and builders in the valley to elicit feedback on the program and the future of energy codes in Mt. Crested Butte. 

The EEOP Calculator Tool allows the user to input data, such as square feet of snow melt or the size of an exterior hot tub. The tool will then calculate the outputs in annual energy use (BTU) and in the PV offset amount in kilowatts (kW).

Hessler explained for single-family homes, there are three “tiers” that apply to the program. Tier 0 is approximately the equivalent of a 50 square-foot hot tub (the average based on feedback from hot tub installers) and requires no offsets. “Basically, a single-family home can build a hot tub or modest snowmelt system without being required to mitigate,” she said.

Under Tier 1, mitigation is required at a rate of one unit of exterior energy used equal to one unit of solar built on property (or the cost to build that solar). “Examples of this range include a hot tub AND an outdoor fireplace AND a heated parking pad AND additional wiggle room for heat tape, additional heated walkway, etc.” said Hessler. Using the calculator for example,

“If a homeowner wanted to install 324 square feet of heated driveway (two parking spots) and a normal sized hot tub, they would be required to mitigate that driveway ONLY, with 6.24 kW of solar or a $27,450 fee in lieu.”

For Tier 2 or the cap, the exterior energy installed cannot exceed 150 million BTUs. “There is no option to pay to offset or build renewable energy here,” said Hessler. “This is only triggered with a snowmelt system of about 1,300 square feet (which is a pretty huge driveway).” She explained that if someone is at the absolute cap of 150 million BTU, the absolute maximum cost to mitigate is approximately $100,000 or 24 kW of solar. For reference, the new Oh Be Joyful solar array by the Baxter Gulch trailhead outside of Crested Butte is 1.125 megawatts.

Hessler said that for commercial properties, Tier 0 is set at one 65 square-foot hot tub per 10 residential units, and there is no commercial cap. “A commercial property could potentially install an unlimited amount of snowmelt, as long as they are mitigating it via solar or payment of the fee in lieu.”

The EEOP Tool will be available for free download on the town’s website once the program goes into effect. Hessler said that less than 10 towns have an EEOP. “What makes this specific program different from other jurisdictions, many of which have this type of program, including Crested Butte, is that our overall allowable exterior energy use (cap), is more restrictive than any other jurisdiction that we know of. It’s very progressive and exciting.”